This application claims the priority of German application 197 07 813.3-12 filed in Germany on Feb. 27, 1997, the disclosure of which is expressly incorporated by reference herein.
The invention relates to an arrangement for connecting pipe pieces, particularly pipe pieces in exhaust systems of motor vehicles having end sleeves which are in each case fastened to the ends of the pipe pieces and point in each case to the other pipe end, in the interior of the end sleeves bellows being arranged and the ends of the bellows being in each case connected with a pipe piece, and with a spring which extends at least partially along the outer circumferential walls of the end sleeves and connects two pipe pieces with one another.
An arrangement of this type, by means of which a flexible connection between pipe pieces is achieved, is known from German Patent Document DE 42 33 644 A1. In this case, the connection of the two pipe pieces takes place by a coil spring placed on the exterior side over the end sleeve. In this manner, the two pipe pieces are connected with one another in a resilient and articulated manner, whereby they are uncoupled with respect to vibrations. This means that relative movements, oscillations and vibrations between the pipe pieces are uncoupled. For damping the vibrations, a damping insert is provided which radially encloses bellows, which provide gas tightness for the pipe pieces. Above the damping insert, the coil spring is arranged which transmits the forces occurring in the axial longitudinal direction and simultaneously exercises a prestressing into an initial center position.
For fixing the position, the coil spring is welded at several points to the end sleeves.
However, in the case of this arrangement, it is a disadvantage that it has a relatively large outside diameter. Furthermore, the damping properties of the damping insert, which preferably consists of a metallic mesh, woven, texture or knit, may change in the course of the operation.
The present invention is therefore based on the object of providing an arrangement of the initially mentioned type which has good damping properties while it requires little space.
According to the invention, this object is achieved by providing an arrangement of the above noted type wherein the spring is constructed as a stranded spring which extends helically along the outer circumferential walls of the end sleeves and which is at least partially covered on an exterior side by protection sleeves which have corrugations adapted to a course of a helical line of the stranded spring, the stranded spring being guided in the corrugations, and wherein the protection sleeves are connected with the end sleeves and ends of the stranded spring are connected with one of the protection sleeves and the end sleeves.
It was found that a stranded spring in connection with the protection sleeves for its guiding and positioning is particularly suitable for a flexible connection of pipe pieces of the initially mentioned type. Because of the further development of stranded springs, these have very good damping properties so that a separate damping device is not required. This means that not only a low-cost construction can be achieved but also an arrangement which requires less space. However, for the operability of the stranded spring, it had to be provided that it cannot "turn out" during the operation. This is achieved by its positioning and guiding in the corrugations. Inside the corrugations, the stranded spring wire can absorb torsional movements, in which case, by means of the friction of the individual spring wires or strands among one another and in the corrugations of the protection sleeve, a very good damping effect is achieved, so that further damping measures are not required.
Another advantage of the use of a stranded spring according to the invention is the fact that it has a longer service life than coil springs. Furthermore, an additional protective effect, which also has a positive effect on the durability of the arrangement, is achieved by means of the protection sleeves surrounding the stranded spring on the exterior side.
In the following, an arrangement is described for connecting pipe pieces in an exhaust system of a motor vehicle. However, this connecting arrangement is basically also suitable for other uses in which an uncoupling of pipe pieces is also important.